1. Field of the Invention
This invention relates to a surface discharge-scheme alternating current-type plasma display panel and, more particularly, to a panel structure for causing a selective discharge in an addressing period.
The present application claims priority from Japanese Application No. 2001-198426, the disclosure of which is incorporated herein by reference for all purposes.
2. Description of the Related Art
In recent time, a surface discharge-scheme alternating current-type plasma display panel which has been developed as a slim, large sized color screen display has become commonly used in ordinary household.
FIG. 10 is a schematic plan view of a conventional cell structure of the surface discharge-scheme alternating current-type plasma display panel. FIG. 11 is a sectional view taken along the Vxe2x80x94V line of FIG. 10. FIG. 12 is a sectional view taken along the Wxe2x80x94W line of FIG. 10.
In FIGS. 10 to 12, the plasma display panel (hereinafter referred to as xe2x80x9cPDPxe2x80x9d) includes a front glass substrate 1, serving as the display surface of the PDP, having on its back surface, in order, a plurality of row electrode pairs (Xxe2x80x2, Yxe2x80x2), a dielectric layer 2 covering the row electrode pairs (Xxe2x80x2, Yxe2x80x2), and a protective layer 3 made of MgO and covering the back surfaces of the dielectric layer 2.
The row electrode Xxe2x80x2 and the row electrode Yxe2x80x2 of each row electrode pair (Xxe2x80x2, Yxe2x80x2) are respectively constructed of transparent electrodes Xaxe2x80x2, Yaxe2x80x2 each of which is formed of a transparent conductive film of a larger width made of ITO (Indium Tin Oxide) or the like, and bus electrodes Xbxe2x80x3, Ybxe2x80x2 each of which is formed of a metal film of a smaller width compensating for electrical conductivity of the corresponding transparent electrode.
The row electrodes Xxe2x80x2 and Yxe2x80x2 are arranged in alternate positions in the column direction so that the electrodes Xxe2x80x2 and Yxe2x80x2 of each pair (Xxe2x80x2, Yxe2x80x2) face each other with a discharge gap gxe2x80x2 between. Each of the row electrode pairs (Xxe2x80x2, Yxe2x80x2) forms each display line (row) L in the matrix display.
The front glass substrate 1 is situated opposite a back glass substrate 4. A discharge space Sxe2x80x2 filled with a discharge gas is interposed between the substrates 1 and 4. The back glass substrate 4 is provided with a plurality of column electrodes Dxe2x80x2 which are arranged parallel to each other and each extend in a direction at right angles to the row electrode pair (X, Y) (the column direction), band-shaped partition walls 5 each extending in parallel to and between the two column electrodes Dxe2x80x2, and phosphor layers 6 provided for emitting the primary colors red (R), green (G), and blue (B), each of which covers the side faces of adjacent partition walls 5 and the column electrode Dxe2x80x2.
In each display line L, the partition walls 5 partition the discharge space Sxe2x80x2 into areas each corresponding to an intersection of the column electrode Dxe2x80x2 and the row electrode pair (Xxe2x80x2, Yxe2x80x2), to define discharge cells (unit light emitting areas) Cxe2x80x2.
Such surface discharge-scheme alternative current PDP displays images through the following procedure.
First, in the addressing period, an operation pulse is applied to any one (assumed as the row electrode Yxe2x80x2 in this case) of the row electrode pair (Xxe2x80x2, Yxe2x80x2), and a data pulse is applied to the column electrode Dxe2x80x2, to selectively cause discharge between the row electrode Yxe2x80x2 and the column electrode Dxe2x80x2.
As a result, lighted cells (the discharge cell Cxe2x80x2 in which the wall charge is formed on the dielectric layer 2) and non-lighted cells (the discharge cell Cxe2x80x2 in which the wall charge is not formed on the dielectric layer 2) are distributed over the panel surface in accordance with an image subject to be displayed.
After completion of the addressing period, a discharge sustaining pulse is simultaneously applied alternately to the row electrode pair (Xxe2x80x2, Yxe2x80x2) in all the display lines. In each application of the discharge sustaining pulse, a surface discharge (sustaining discharge) is caused in each lighted cell.
In this way, the surface discharge generates ultraviolet light in the lighted cells. The generated ultraviolet light excites the phosphor layer 6 in each lighted cell to thereby emit light of the three primary colors red (R), green (G) and blue (B) for forming a display image.
However, such a conventional display panel has a problem of reduced yields of the lighted cells (or non-lighted cells) resulting from the selective discharge because the selective discharge in the addressing period is caused in the discharge cell Cxe2x80x2 over an entire face of a part, overlaying the column electrode Dxe2x80x2 when viewed from the front glass substrate 1, of one of the row electrode pair (the row electrode Yxe2x80x2 assumed in this case). Hence, a discharge area is disadvantageously increased to make the selective discharge unstable.
The present invention has been made to solve the problem associated with the surface discharge-scheme alternating current-type plasma display panel as described above.
Accordingly, it is an object of the present invention to provide a plasma display panel capable of producing stable selective discharge to generate high quality images.
To attain the above object, according to a first feature of the present invention, a plasma display panel includes: a front substrate; a back substrate placed opposite to the front substrate to define a discharge space between the front and back substrates; a plurality of row electrode pairs extending in a row direction and arranged in a column direction on a back surface of the front substrate to respectively form display lines; and a plurality of column electrodes arranged in the row direction on a surface, facing toward the front substrate, of the back substrate, and extending in the column direction to intersect the row electrode pairs and form unit light emitting areas in the discharge space at the respective intersections, which comprises: a leading member provided in each paired row electrodes of the row electrode pairs and facing each other with a discharge gap there-between in each unit light emitting area; and an enlargement member provided in the column electrode at a position opposite to at least one of leading members of the paired row electrodes in each unit light emitting area, and having a width in the row direction larger than a width of portion of the column electrode opposite to the row electrode except for the leading member opposite to the enlargement member.
In the plasma display panel according to the first feature, in an addressing period when an image is generated on a panel screen on the basis of an image signal, an operation pulse is applied to one row electrode of each row electrode pair and a data pulse is applied to the column electrode. Then, in each unit light emitting area in which the row electrode applied with the operation pulse intersects the column electrode applied with the data pulse, a selective discharge is caused between the row electrode and the column electrode. As a result, lighted cells and non-lighted cells are distributed over the panel surface in accordance with an image to be displayed.
In this addressing period, due to the enlargement member provided in the column electrode, an opposite area of the column electrode to the leading member of the row electrode between which the selective discharge is caused, is significantly enlarged more than an opposite area of the column electrode to the row electrode except for the leading member. Accordingly, the selective discharge is caused concentratedly between the leading member of the row electrode and the enlargement member of the column electrode, which are opposite to each other.
With the first feature, it is possible to prevent the discharge property instability which results from extensively producing, over the entire surface of the row electrode, the selective discharge between the row electrode and the column electrode.
Even when, for example, a partition wall for defining the unit light emitting areas is formed between the front substrate and the back substrate, and the partition wall is overlapped with part of the row electrode undergoing the selective discharge, the discharge properties of the selective discharge can be prevented from being adversely affected by the partition wall, because the selective discharge is caused substantially in a central part of the unit light emitting area.
To attain the aforementioned object, according to a second feature of the present invention, a plasma display panel further comprises, in addition to the configuration of the first feature, a phosphor layer for emitting a different color in each unit light emitting area, in which the enlargement member of the column electrode is changed in width in the row direction to be smaller in order of the colors facilitating the discharge between the row electrode and the column electrode.
With the second feature, the discharge properties of the phosphor layers vary with the colors of phosphor materials used for forming the phosphor layers each of which is formed in each unit light emitting area and is applied with a different color from that of another phosphor layer. Therefore, the enlargement member provided in the column electrode is designed to have a small width in the row direction in the unit light emitting area which is provided with the phosphor layer applied with a color facilitating the discharge between the row and column electrodes, and to have a larger width in the unit light emitting area which is provided with the phosphor layer applied with a color resistant to cause the discharge between the row and column electrodes. With such design, the discharge properties varied among the colors of the phosphor layers are adjusted to cause a uniform selective discharge in each unit light emitting area.
To attain the aforementioned object, according to a third feature of the present invention, in addition to the configuration of the second feature, the enlargement member of the column electrode has, in the row direction, a small width of a side facing toward the unit light emitting area provided with the red phosphor layer, and a larger width of a side facing toward unit light emitting area provided with the blue phosphor layer, and a much larger width of a side facing the unit light emitting area provided with the green phosphor layer.
With the third feature, regarding the red, blue and green phosphor layers formed in the individual unit light emitting areas, phosphor materials used for forming the red phosphor layer facilitates the discharge, but phosphor materials used for forming the green phosphor layer is resistant to cause the discharge. Coping with such phosphor materials, the plasma display panel provides a smaller width for the enlargement member of the column electrode positioned in the unit light emitting area provided with the red phosphor layer, and a larger width for the enlargement member positioned in the unit light emitting area provided with the green phosphor layer. With this manner, the variations of the discharge properties according to the colors of the phosphor are adjusted to cause a uniform selective discharge in each unit light emitting area.
To attain the aforementioned object, in a plasma display panel according to a fourth feature of the present invention, in addition to the configuration of the first feature, the enlargement members are provided in pair in the column electrode at respective positions opposite to the leading members of the paired row electrodes in each unit light emitting area, and having a width in the row direction larger than a width of portion of the column electrode opposite to the row electrode except for the leading member opposite to the enlargement member.
With the fourth feature, the enlargement member provided in a portion of the column electrode opposite to the leading member of the row electrode undergoing the selective discharge, serves as a function of concentrating of the selective discharge into a substantially central part of the unit light emitting area, to prevent the discharge properties of the selective discharge from becoming unstable. In addition, when lighted cells are selected by means of the selective discharge in a selective erase scheme, and then discharge is continuously caused between one of the row electrodes paired, which has undergone the selective discharge together with the column electrode, and the other row electrode in each unit light emitting area, the plasma display panel facilitates the later discharge due to one of the enlargement members provided in pair in the column electrode which is opposite to the leading member of the other row electrode.
To attain the aforementioned object, in a plasma display panel according to a fifth feature of the present invention, in addition to the configuration of the first feature, the enlargement member is provided in the column electrode at a position opposite to both of the leading members of the paired row electrodes in each unit light emitting area, and having a width in the row direction larger than a width of portion of the column electrode opposite to the row electrode except for the leading members opposite to the enlargement members.
With the fifth feature, the enlargement member provided in the column electrode so as to be opposite to the leading member of the row electrode undergoing the selective discharge, serves as a function of concentrating of the selective discharge into a substantially central part of the unit light emitting area, to prevent the discharge properties of the selective discharge from becoming unstable. In addition, when lighted cells are selected by means of the selective discharge in a selective erase scheme, and then discharge is continuously caused between one of the row electrodes paired, which has undergone the selective discharge together with the column electrode, and the other row electrode in each unit light emitting area, the plasma display panel facilitates the later discharge due to the enlargement member provided in the column electrode which is opposite to the leading member of the other row electrode.
To attain the aforementioned object, according to a sixth feature of the present invention, in addition to the configuration of the first feature, the plasma display panel further comprises phosphor layers for emitting different colors, each provided in each unit light emitting area and having a larger thickness as the phosphor layer more facilitates the discharge between the row electrode and the column electrode.
With the sixth feature, the discharge properties of the phosphor layers vary with the colors of phosphor materials used for forming the phosphor layers each of which is formed in each unit light emitting area and is applied with a different color from that of another phosphor layer. Therefore, the phosphor layer is set for each unit light emitting area to have a larger thickness when being applied with a color facilitating the discharge between the row and column electrodes, and to have a smaller thickness when being applied with a color resistant to cause the discharge between the row and column electrodes. With such varying in thickness, the discharge properties varied among the colors of the phosphor layers are adjusted to cause a uniform selective discharge in each unit light emitting area.
To attain the aforementioned object, according to a seventh feature of the present invention, in addition to the configuration of the sixth feature, the phosphor layer is reduced in thickness in order of the unit light emitting area provided with the red phosphor layer, the unit light emitting area provided with the blue phosphor layer, and the unit light emitting area provided with the green phosphor layer.
With the seventh feature, when the red, blue and green phosphor layers are formed in the individual unit light emitting areas, phosphor materials used for forming the red phosphor layer facilitates the discharge, but phosphor materials used for forming the green phosphor layer resistant to cause the discharge. Coping with such phosphor materials, the plasma display panel is designed such that the red phosphor layer has a largest thickness and the green phosphor layer has a smallest thickness, in order to adjust the discharge properties varied with the colors of the phosphor layer, thereby achieving a uniform selective discharge caused in each unit light emitting area.
To attain the aforementioned object, in a plasma display panel according to an eighth feature of the present invention, in addition to the configuration of the first feature, the row electrodes of each of the row electrode pairs respectively include main bodies extending in the row direction, and jutting sections extending from the respective main bodies in the column direction to face each other with the discharge gap there-between in each of the unit light emitting areas, and respectively having base members connected to the respective main bodies, and the leading members facing each other and each having a width larger than that of the base member, in which the enlargement member of the column electrode is opposite to the leading member having the larger width of the jutting section of one of the paired row electrodes.
With the eighth feature, in each unit light emitting area, each of the leading members facing each other is provided with an increased width in the independent, so-called island-shaped jutting section of each row electrode. The selective discharge in the addressing period is carried out between the increased width leading member of the jutting section and the corresponding enlargement member of the column electrode. Accordingly the selective discharge is caused concentratedly in a substantially central part of each unit light emitting area, leading to a further stabilized discharge properties.
To attain the aforementioned object, according to a ninth feature of the present invention, in addition to the configuration of the first feature, a plasma display panel further comprises a partition wall between the front substrate and the back substrate, having vertical walls each extending in the column direction and transverse walls each extending in the row direction, and provided for partitioning the discharge space, defined between the front and back substrates, in the row and column directions to define the unit light emitting areas.
With the ninth feature, the discharge space defined between the front and back substrates is partitioned into quadrangles by the vertical walls extending in the column direction and transverse walls extending in the row direction of the partition wall, to define the unit light emitting areas. The selective discharge is carried out between the leading member of one row electrode of each row electrode pair and the enlargement member of the column electrode in each unit light emitting area defined by the partition wall.
These and other objects and features of the present invention will become more apparent from the following detailed description with reference to the accompanying drawings.